A current sensor for detecting a magnetic field generated by current, a rotation angle sensor for detecting rotation of a magnet, a position sensor for detecting movement of a magnet, and the like have been known as a magnetic-sensor semiconductor integrated circuit having a Hall device built therein.
FIG. 1 is a diagram illustrating an example of a drive circuit of a Hall device. When Hall drive current IH flows from Electrode 1 to Electrode 3, it can be seen that a Hall device output VH is obtained between Electrode 2 and Electrode 4.
Methods of driving a Hall device are generally classified into two types of a constant-current drive method and a constant-voltage drive method. A method in which the Hall drive current IH is kept constant in FIG. 1 is the constant-current drive method, and a method in which a Hall drive voltage Vd is kept constant is the constant-voltage drive method. Magnetic sensitivities in the drive methods are referred to as a constant-current sensitivity and a constant-voltage sensitivity, respectively.
In general, a Hall device has a configuration in which an n-type impurity region is disposed on the surface of a p-type semiconductor substrate layer formed of p-type silicon. The n-type impurity region serves as a magnetosensitive portion.
For example, Patent Document 1 discloses a vertical Hall device that can enhance a degree of freedom in selecting a substrate used to form a Hall device and a manufacturing method thereof. The vertical Hall device is formed on a semiconductor substrate formed of P-type silicon and outputs a Hall voltage signal corresponding to a magnetic field component when the magnetic field component parallel to the surface of the semiconductor substrate is applied to a magnetic detection portion HP in a state where a current including a component perpendicular to the surface of the semiconductor substrate is supplied to the magnetic detection portion HP in an N-type semiconductor region 12.
Patent Document 2 discloses that a concentration of an n-type impurity region suitable for an azimuth sensor is in a range of 1.0×1016≦N≦3.0×1016 (atoms/cm3) in order to improve an SN ratio.
Patent Document 3 discloses a method of inspecting a 5-point temperature inspection in a pre-shipment test, recording the inspection result on an EEPROM, and correcting a polygonal line of 5-point temperatures to achieve an increase in detected magnetic field accuracy.
Patent Document 4 discloses a concentration distribution in the depth direction of an N-type region in an electrode portion of a Hall device. The N-type impurity concentration ranges from 5×1017 atoms/cm3 to 3×1019 atoms/cm3 within the range of the concentration distribution, that is, the range of 0.3 μm to 0.5 μm in the depth direction.